1. Field of the Invention
The present invention relates to manually operated reciprocating pumps for containers for spraying and atomizing liquids.
2. Background of the Invention
A conventional spray pump for dispensing liquids from a container includes a hollow body having openings in each end, into the upper end of which is fitted a hollow piston which is slidable reciprocally in the body with sealing fit, which piston is connected at its upper end to an actuator. The piston and body define an interior chamber having an opening at each end. The upper opening of the piston connects with a nozzle of the actuator from which the liquid is dispensed. An outlet valve is located in the upper opening. An inlet valve is located in the lower opening in the lower end portion of the body. Such valves may be ball valves, for example as disclosed in U.S. Pat. No. 3,963,150, or they may have other shapes, such as a planar valve element as disclosed in U.S. Pat. No. 3,991,914. Such valves are typically dependent on liquid pressure causing the ball to move away from the valve seat.
Typically, during a dispensing stroke of the piston, force is applied to the actuator, which causes the piston to slide downwardly into the body, causing the piston chamber to decrease in size and the pressure inside the chamber to increase. The liquid pressure inside the chamber causes the upper valve to open, while the lower valve is held closed by the same pressure, so that liquid flows out of the chamber through the open upper valve and is dispensed from the actuator. A spring is provided to return the piston to an up position when the actuator is released. During an upward stroke, a vacuum is formed in the chamber causing the lower valve to open so that liquid is drawn through the opening in the lower end of the body into the chamber.
In other pumps, frictional interengagement of the moving pump elements can cause the pump to operate, as disclosed in U.S. Pat. No. 4,606,479.
It is desirable to provide a pump with a low profile, so that the pump piston does not extend a long way above the container, and so that the pump body does not extend a significant distance into the container. However, the aforementioned pumps generally have required a substantial length to accommodate the stroke length needed to achieve the necessary shot size, and have thus required long piston sections.
These problems are addressed and resolved by the present invention as set forth hereafter.